Open end spinning device



y 9 A. SCHILTKNECHT ETA!- 3,511,043

OPEN END SPINNING DEVICE Filed Sept. 25, 1968 2 Sheets-Sheet 1 Fig.2

INVENTORS HDOLF'SCH/LTKNECHT MAX eenF BY flTT'OR May 12, 1970 A. S'CHILTKNECHT ET AL 35 I OPEN END SPINNING DEVICE Filed Sept. 25, 1968 2 Sheets-Sheet 2 INVENTORS A004 F saw/z TAA/ECHT MAX 686 United States Patent 3,511,043 OPEN END SPINNING DEVICE Adolf Schiltknecht and Max Graf, Winterthur, Switzerland, assignors to Rieter Machine Works, Ltd., Winterthur, Switzerland, a corporation of Switzerland Filed Sept. 23, 1968, Ser. No. 761,425 Claims priority, application Switzerland, Sept. 27, 1967, 13,592/ 67 Int. Cl. D01h 7/00 US. Cl. 5758.89 10 Claims ABSTRACT OF THE DISCLOSURE The rotor is constructed with a cross-duct below the fiber collecting surface which communicates radially with the exterior of the rotor. The cross-duct is wider across the rotor center than the opening communicating the cross-duct with the fiber collecting surface and is of decreasing cross-sectional area towards the rotor periphery.

This invention relates to an open end spinning device and more particularly to an open end spinning device having a self-generating evacuation means.

Basically, two types of rotors for open end spinning devices can be distinguished, namely rotors which selfgenerate a vacuum and rotors with separate external suction devices wherein the vacuum inside the rotor is created by a separate fan. Further, combinations of both rotor types can be constructed. In order to evacuate the interior fiber collecting surface of the rotors, suction can be effected between a cover over the rotor or through a hollow axle carrying the rotor, the speed of such rotors generally exceeding 15,000 r.p.m. At such high rotational speeds, however, contamination caused by speed particles, fiber debris, etc. builds-up quickly and can cause yarn irregularities and excessive ends down. Also, startup and stopping as well as piecing operations are not easily controlled in such rotors. Before starting and after stopping the rotor necessarily is at a stand-still. Thus, in the absence of centrifugal forces retaining the fibers and the yarn end in the rotor groove, disturbances of the fiber arrangement, krinkling of the yarn end and unwanted slipping of the yarn end out of the rotor can occur.

In rotors which self-generate their suction through perforations in the rotor, the danger exists that the perforations become clogged by trash and fibers while in rotors which are provided with external suction acting along the cover, the air is forced through a narrow gap between the cover and rotor so that, e.g. the fibers not twisted into the yarn, are not eliminated. In both cases, the rotor housing must be opened for cleaning of the rotor. Furthermore, the position of the yarn end after stopping, or at starting up respectively, is not defined in rotors of the self-generating suction type, whereas in rotors provided with axial suction, the yarn end can be extended in the hollow axle and can be held therein if needed.

Compared to the aforementioned rotor types, rotors provided with suction through the hollow axle are advantageous, as vigorous suction during a rotor stand-still permits removal of fiber debris, seed particles and fiber not yet spun into the yarn. Also, certain yarn quality advantages can be achieved by means of axial suction as the fiber arrangement can be improved by clearly defined air currents. Unfortunately, however, axial suction also has severe disadvantages. For example, a very strong vacuum of the order of 600 to 800 mm. water column must be maintained by the suction fan if the air volume needed is to be forced through the hollow rotor axle, the diameter of which must be kept relatively small because of the bearing design for such.

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A combination of a rotor with a fan is known in which the rotor is provided with a centrally perforated base and with a fan below the rotor base. In this combination yarn formation is effected in the fiber collecting chamber above the rotor base and the vacuum is created in the chamber below the rotor base by a fan formed by radial holes with the vacuum drawn from the upper chamber via the central perforation of the rotor base. This device avoids the substantial pressure drop needed for sucking the air through a hollow rotor axle. Unfortunately, manufacture of such rotors is impractical and the dimensions are lim ited. Also, building such rotors from several components designed for simplified manufacturing, results in unfavorable stress distributions. Furthermore, the fan chamber below the rotor base is practically inaccessible for cleaning purposes and the relatively small radial holes forming the fan easily tend to clog up and where fan blades are substituted for the radial hole arrangement, fiber tufts can still accumulate and be retained in the lower chamber by centrifugal forces. Such fiber accumulations can also create undesirable eccentricities which can cause overheating and premature break-down of the bearings of the rotor.

Accordingly, it is an object of the invention to achieve the advantages of a rotor provided with suction through an opening in the rotor base without clogging and contamination.

It is another object of the invention to provide a rotor which is evacuated through an opening in the base which can be easily cleaned.

Briefly, the invention provides a rotor of an open end spinning device with a cross-duct located centrally below the fiber collecting surface in the rotor. The cross-duct communicates with the fiber collecting surface through a central aperture therebetween and functions as a vacuum generating fan to evacuate the fiber collecting sur face.

In one embodiment, the cross-duct extends substantially diametrically across the rotor with a decreasing cross-sectional area from a point centrally of the rotor towards the rotor periphery. The cross-duct can have opposite side walls which are convex with respect to each other or which follow a serpentine path. In either case, the cross-duct is of larger width than the opening communicating with the fiber collecting surface.

In another embodiment, the cross-duct has a plurality of legs, for example, three or four, which extend radially from a central area of the cross-duct. Each leg is of decreasing cross-sectional area towards the rotor periphery while the sidewalls between adjacent legs are convex in shape.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIGS. 1 to 3 respectively illustrate cross-sectional views of prior open end spinning devices;

FIG. 4 illustrates a cross-sectional view taken on line IVIV of FIG. 5 of a rotor having a cross-duct according to the invention;

FIG. 5 illustrates a view taken on line VV of FIG.

FIGS. 6 to 8 respectively illustrate cross-sectional views similar to FIG. 5 of other modifications of a cross-duct according to the invention;

FIGS. 9 and 10 respectively illustrate perspective views of further modified rotors with cross-ducts according to the invention; and

FIGS. 11 and 12 respectively illustrate cross-sectional views of rotors employing cross-ducts of different crosssectional shapes according to the invention.

Referring to FIGS. 1 to 3, the heretofore known open end spinning devices have, in some instances, mounted a rotor 3 in a housing 2 which is evacuated through a suction duct 1 (FIG. 1). Sucha rotor 3 has been provided with an interior fiber collecting surface 4 in the shape of a fiber groove 5 which takes up the fibers fed in via a duct 6. Also, a cover 7 is positioned in the housing 2 over the rotor 3 to cover the open end. In order to create a vacuum in the rotor 3, a plurality of radial holes 8 have been formed in the groove 4. In another instance (FIG. 2), the vacuum acts via a hollow rotor axle 9 into the rotor. 'In still another instance (FIG. 3), a plurality of holes 11 for generating the vacuum are arranged separately from the actual fiber collecting surface 12 in a seperate chamber connected with the collecting surface chamber by an opening 13.

Referring to FIGS. 4 and 5, a rotor 19 according to the invention is provided with a cross-duct 16 in a separate chamber below a fiber collecting surface 14 of the rotor 19. The cross-duct 16 is connected with the collecting surface 14 by a central opening 15 and is wider across the rotor center than the opening 15. Further, the walls 17, 18 of the cross-duct 16 are concave in shape so that the cross-sectional area decreases towards the rotor periphery. The curvature of these concave walls should be kept within the limits specified in the following.

As shown in FIG. 5, the straight lines G, G through the center K of the wall curvature and forming tangents of the opening 15 meet the wall surface 17 in points A and B respectively. The tangents of the wall curvature in these point A and B enclose an angle a which, as proven by tests, must exceed 120 degrees if clogging is to be safely prevented. The curvature of the opposite wall 18 must also fulfill the same conditions. The distance A between walls 17 and 18 across the rotor center should also not exceed 225 percent of the maximum diameter D of the opening 15 which can, for example, be elliptical.

The upper surface limiting the cross-duct 16 is defined by the rotor base plate 20 which forms a right angle with the rotor axis, whereas the lower surface 19 limiting the cross-duct 16 forms an angle 7 of approximately 80 degrees with the rotor axis. This angle 7, however, should not be chosen smaller than 45 degrees. Such ducts will not permit any accumulation of fibers sucked accidentally from the fiber collecting surface 14 and thus danger of clogging is eliminated.

Referring to FIG. 6, the cross-duct can also be made with multiple legs, for example, three. In this case, the legs extend radially from the center of the rotor towards the outside. Further, the walls 21, 22, 23 of the legs are convex in shape to permit the cross-sectional areas of the legs to decrease towards the rotor periphery and are tangent to the plane of the central opening leading to the fiber collecting surface. In order to avoid fiber accumulation within the cross-duct, the angle B between the tangents t t, of adjacent walls 21, 22, 23 exceeds 120. As shown, the angle 5 is 150.

Referring to FIG. 7, the multi-leg cross-duct can also be provided with four legs. In this case, as shown, the angle 18 is 140.

Referring to FIG. 8, the rotor can be provided with an asymmetric cross-duct 24 wherein half of each side wall is concave and convex, respectively. In addition, the half portions of each side wall of the cross-duct 24 are shaped in a manner as above, symmetrical supplements of the wall portions being imagined for determination of the angles a and 5. As shown, the angle a can also be determined by measuring the angle a/2.

Referring to FIG. 9, the rotor is provided with a crossduct formed by a tube section 25 mounted on the underside of the rotor wherein the cross-sectional area remains constant.

Alternatively, referring to FIG. 10, the tube section 25 mounted on the rotor to form the cross-duct can be shaped rectangularly.

Referring finally to FIGS. 11 and 12, the cross-duct 2'6, 26' in communication with the fiber collecting surface can also have a trapezoidalcross-section (FIG. 11) or a circular cross-section (FIG. 12).

What is claimed is:

1. A rotor for an open end spinning device comprising a fiber collecting surface,

a central opening in said surface, and

a cross-duct spaced from said surface and in communication with said surface through said opening, said cross-duct being disposed across the center of the rotor to generate a vacuum within said surface upon rotation of the rotor.

2. A rotor as set forth in claim 1 wherein said crossduct is of greater width than said opening in the area of said opening.

3. A rotor as set forth in claim 2 wherein said crossdiuct has a pair of sidewalls on opposite side of said opening, said walls Ibeing spaced apart across the rotor center a distance not more than 125 percent of the maximum width of said opening.

4. A rotor as set forth in claim 1 wherein said crossduct is of decreasing cross-sectional area towards the rotor periphery.

5. A rotor as set forth in claim 4 wherein said crossduct has a pair of opposite sidewalls, each of said walls being concave.

6. A rotor as set forth in claim 5 wherein the tangents to each said concave wall at the points of intersection of two radii of the curvature of said wall tangent to said opening form an angle greater than 120.

7. A rotor as set forth in claim 1 wherein said crossduct includes a plurality of radially directed legs.

8. A rotor as set forth in claim 7 wherein each pair of adjacent legs have a common wall portion, said wall portion being convex.

9. A rotor as set forth in claim 8 wherein the tangents to each said common wall portion at the points of intersection of two radii of said wall portion curvature tangent to said opening form an angle of at least 120.

10. A rotor as set forth in claim 1 wherein said crossduct has an upper surface and a lower surface, each said surface defining an angle with the axis of the rotor of between 45 and References Cited UNITED STATES PATENTS 3,339,359 9/1967 Ripka et al. 5758.89 3,357,168 12/1967 Zlevor et al. 5758.89 3,367,099 2/1968 Kubovy et al 5758.89 3,447,298 6/1969 Collins 5758.89

DONALD E. WATKINS, Primary Examiner 

